Off-peak water heating system



94 H. M. BIEBEL 2,266,148

OFF-PEAK WATER HEATING SYSTEM Filed March 27, 1941 ay-f IIII III

INVENTOR. /%'RMA /v B/EBEL BY ATTORNEY.

Patented Dec. 16, 1941 OFF-PEAK WATER HEATING SYSTEM Herman M. Biebel, Elgin, m, assignmto McGraw Electric Company, Elgin, 111., a corporation of Delaware Application March 27, 1941, Serial No. 385,448-

3 Claims.

My invention relates to electric heating systems and particularly to off-peak water heating systems for domestic hot water tanks.

An object of my invention is to provide a relatively simple hot water heating system for controlling the energization of a heater applied to an ,ordinary domestic hot water tank.

another object of my invention is to provide an oil-peak water heating system embodying a minimum number of relatively simple component operating parts and effective to either start energization of a tank heating element at the start of an off-peak period or to delay said energization in accordance with the "amount of hot water in the tank.

Other objects of my invention will either be apparent from a description of a system embodying my invention or will be pointed out during such description and set forth in the appended claims.

In the single sheet of drawings:

Figure 1 is a diagrammatic view of a system embodying my invention shown generally only and asapplied to a domestic hot water tank, and, I

Fig. 2 is a fragmentary view of a modified form of elements embodying my invention.

'I have shown an ordinary hot water tank of the ordinary cylindrical elongated type pro- I may locate the heater in a tunnel member 23.-

' I desire it to be understood, however, that these details constitute no part of my invention and may be changed as desired for other details of construction effective for the same purpose.

I provide a thermal heater control switch 25 here shown as embodying a bimetal bar 21 having one end thereofmounted on a fixed contact. or support subject to the temperature of either the tank or of the'water in the tank. The free end of bimetal bar 21 may engage and move away from a fixed contact member- 29. Here again I and having a worm gear mounted on its shaft. The worm gear is adapted to mesh with and drive a worm wheel 31 which is shown as being mounted on and rotatably supported by a shaft 39. The details of the continuously operative timer are general only and are intended to rep resent a timer or timing means operative to cause rotation of the shaft 39 through one complete revolution during a twenty-four hour period.

I provide an electric conducting member. 4| of substantially cylindrical form which may be insulatedly mounted on shaft 39. While I have not shown any supporting bearings for the shaft 39, these are to be understood as being provided, all in a manner well known in the mechanical art. The greater portion of the periphery of member 4| has a certain uniform outer radius and this portion 43 represents the on-peak period while an off-peak period is represented by a portion 45 which has a somewhat larger outer radius. As shown by the arrow on the end face of member 4|, it is to be understood as being turned in a clockwise direction by the transmitting means connecting it with the motor 33. While the trailing edge of portion 45 extends in a straight axial direction, the leading edge 41 of portion 45 extends angularly relatively to the longitudinal axis of said shaft 39. This is for a purpose which will presently appear.

I provide a thermally responsive means 5| on the tank II as by supporting the upper end of a metallic bar 5| having a relatively small oodesire to point out that the thermal heater control switch 25 is shown generally only, for illustrative purposes, and any other thermal switch now known in the art may be used by me in place of the switch shown in'the drawing.

eflicient of expansion with increase of temperature, by a bracket 53 supported from or secured to the upper end of tank The lower end of bar 5| has teeth therein to constitute a rack bar meshing with a pinion 55 which is shown generally as being rotatably supported by a bracket member 51 which is supported from the lower end of tank When the water in the tank is hot the lower end of thermal element 5| is farther from the lower end of the tank than it is when the tank contains an appreciable amount of cold water or is entirely filled with cold water so-that a shaft 59 on which pinion 55 is fixedly mounted will be caused to turn in accordance with changes in the temperature of the water in the tank; It will be noted that the thermal element 5| is adapted to integrate the temperature of theflvater in the tank or to be responsive to the average temperature of the water in the tank or to the heat content of the tank since, as above stated, I prefer to use a non-expansible member and to permit the expansion and contraction of the tank in a longitudinal direction to vary the relative position of the lower end of member 5|. Shaft 59 has mounted thereon a gear segment 6| which is adapted to mesh with a movably supported rackbar 63. This rack bar may, for instance,

be mounted on a fixedly supported bar 65 so that turning movement of pinion 55, shaft 59,

and gear segment 6i will cause movement of the rack bar member 63 longitudinally along its support 65. While no specific supports are shown for the bar '65, it is to be understood that any suitable means of supporting this bar will be provided. It may here be noted that these members are shown on an enlarged scale for the sakeof clearness.

A contact arm or spring brush Bl is insulatedly mounted on, supported by and movable with the rack bar 63 and it is to be pointed out that this movement of brush 6? is in a substantially axial direction relatively to the length of member M or axially of shaft 39.

I have indicated a pair of supply circuit conductors 59 and H as well as an electromagnetic heater control switch including a coil it, a magnetizable core member 55.8. main contact bridging member Ill and an auxiliary contact bridging member '59 suitably mechanically connected with core member 15. The main bridging member ll is adapted to be engaged with and disengaged from a pair of fixed contact members 8!] while the auxiliary bridging member it is adapted to engage with and be disengaged from fixed 'fore to the 'fixed end of bimetal bar 2?. Supply circuit conductor 69 is connected by a conductor 95 with a-brush 9? supported in such manner as to be in continuous electric engagementwith member ti.

Let it be assumed that the tank contains a relatively large amount of cold water which would v result in the parts hereinbefore described or the thermally'actuable contact member 61! being in the position shown in Fig. 1 of the drawing. The position of member ti rotated continuously by the timing means is that just before the start of an off-peak period and, for illustrative purposes, this may be considered to be at the hour of 10 p. m; with the fulllength of an ofi-peak period being eight hours, so that the off-peak period will be considered to end at 6 a. in. As soon as brush bl engages the leading edge ill of the peripheral portion 55 of member M an circuit conductor 1!. Since one object of my invention is to provide a relatively simple system for effecting energization of the heater of a hot water tank- 'at a time either substantially at the start of an off-peak period in case the tank contains a relatively large amount of cold water or at a later period in an off-peak period, that is, after a certain time interval, the inclined leading edge 47 of the portion 45 together with the adjustable contact member movable in accord= ance with the temperature of the water in the tank will effect such control. I have shown, in the broken lines in Fig. l of the drawing, the position occupied by the contact arm El and its support 63, as well as that of the gear segment iii in case the tank contains a. relatively large amount of .hot water whereby member El has been moved to another position longitudinally of the axis of the shaft 39 whereby engagement by the brush 5i and the leading edge of brush it will be delayed. It may here bepointed out that the design, construction and adjustment of these cooperating elements is such that any desired length of delay period, after the start of an ofi= peak period, may be obtained as on the order of one, two or perhaps more hours.

A holding circuit for coil it was also closed and may be traced as follows: From supply circuit conductor 69 through conductor 85, the enenergizing circuit through coil it will be estab- Y lished'as follows: From supply circuit conductor t9 through conductor 95 and brush fill into and through member M, from there to and through the engaged brush Sland conductor 91!, through coil 13 and through conductor 93, to and through the engaged members 2'? and 29 and from there through the conductor as to the other supply circuit conductor ll. This will cause upward movement of the two contact bridging members, the engagement of contact bridging member '87 with thefixed contact members 8! providing an energizing circuit through the heater'2i substantially asioilows: From supply circuit conductor 89 through conductor db, the engaged contact members 51 and 8 l through conductor 8?, through heater 2| and the thermal switch 25 and from there through conductor tit to the other supply gaged contact members l9 and 53, through a conductor 99 to one terminal of coil it, through conductor 93 and the closed thermal switch 25 and from there through conductor 89 to the other supply circuit conductor ll; It'is obvious that this holding circuit is not dependent on the engagementof brush 8? with portion d5 of member iii so that energization of the coil it will con= tinue beyond the endof an ofi -peak period when brush 6'? is out of engagement with the continuously movable electric conducting surface represented generally by portion 65 of member 5 t.

This operation of the electromagnetic switch is a very desirable on under the following conditions. Let it be assumed that the tank contained a relatively large amount of hot water at the start of theofi-peak period and that the tank was heated at such a rate that bimetal bar 2? moved out of engagement with contact mem= ber 29 to efiect deenergization of the electromagnetic switch and of the heater it sometime, say an hour or so, before the end of the ofi-mak period. At this time. brush t? would still be in engagement with portion it and should it. happen that such an amount of hot water was withdrawn from the tank, before the end of an ofi= peak period, the hereinbefore described energizing circuit through coil 13 and therefore the en-= ergizing circuit through heater 2i would be re= established and even though the continuously operative timer would effect disengagement of the contact portion 45 from brush St at the end of an ofi-peak period, energization of theheater would continue beyond the end of an off-peak period. This energizationof heater 2i would continue until substantially all of the water in the tank is hot.

As it may be desirable to effect energization of the electromagnetic switch and therefore of the heater 2! during an on-peak period, I provide a normally open push button switch lei shown as including a contact bridging member i9 3 adapted to be normally engaged with fixed contact members we. One of these contact members "5 is connected by a conductor it? to conductor 99 and therefore to one terminal of coil 78. The

other fined contact I0! is connected bye conductor I09 with one of the fixed contact members 8| and therefore with conductor 85. Normally pressure on the switch IOI will effect energization of the hereinbefore described circuit through coil 13 and therefore closure of the heating circuit through heater 2I hereinbefore described, as well as the holding circuit hereinbefore described. Thus in case of extraordinary demands for hot water during the day, above and beyond the usual amount for which the elements of the system have been designed and adjusted, the user can obtain a full tank of hot water in case such emergency demand arises.

I have shown, in Fig. l of the drawing, a metal-- lic member 4| but it is to be understood that I may provide a cylindrical member of electric insulating material and mount thereon a contact surface having an angularly extending leading edge and a straight axially extending trailing edge and that a suitable slip ring may be insulatedly mounted on the member of electric insulating material, which slip ring is adapted to be engaged by brush 91, all in a manner well known in the art.

Referring now to Fig. 2-of the drawing, I have there shown a modification of the contact members controlled respectively in accordance with time and with the average or integrated temperature of the water in the tank. I have shown a disk III, of electric insulating material, having fixedly mounted thereon a contact surface II3, the maximum peripheral extent of which is substantially that of the length of an oil-peak period the leading edge I I4 extending angularly relative to a radial line. This disk may be considered to be rotated in a clockwise direction by the electric motor 33 and to be mounted on shaft 39. A slip ring surface I I5 may be provided electrically connected with or a part of contact surface H3 which may be engaged by a contact brush III. Rod ii, a part of the thermally responsive means hereinbefore described, may be connected to the short arm IIB of a bell crank lever pivotally mounted on a fixed pin I2I having a second longer arm I23. A contact arm or resilient brush I25 is fixedly mounted on and supported by arm I23 and if arm I23 is of metal, arm- I25 will be electrically insulated therefrom. The design, construction and location of the parts shown in Fig.

2 of the drawing are such that the arm I25 will occupy substantially the position shown by the full lines in Fig. 2 when the water in the tank has a relatively low average temperature or in case the tank contains a relatively large amount of cold water so that energization of the circuit hereinbefore described will be effected either substantially at the start of an oil-peak period or shortly thereafter. I have shown, in broken lines, the position of elements I23 and I25 which they will occupy. when a relatively large amount of hot water is in the tank and it will be noted that the disk I I I must be' rotated more before engagement of contact I25 with the leading edge Ill of surface II! will occur because of the angular leading edge and the relative movement of contact I28 than would be necessary when the tank contains a relatively large amount of cold water.

My improved oil-peak water heating system including a continuously movable contact surface electrically connected in a control circuit and a cooperating contact responsive to the averageor integrated temperature of the water in the tank, is therefore eifective to energize the heater of a hot water tank at either thestart of an oilpeak period or shortly thereafter or after a delay period, the length of which increases with the amount of hot water in the tank at thestart of an oil-peak period.

Various modifications may be made in the system embodying my invention without. departing from the spirit and scope of the invention and I desire that all such modifications clearly coming within the scope of the appended claims shall be considered to be covered thereby.

I claim as my invention:

1. In an off-peak water heating system for a tank having an electric heater, an electromagnetic switch for said heater, a continuously operative timer, an electric contact plate adapted to be rotated by said timer and having an angularly-extending leading edge, a movable contact brush, thermally-actuable means responsive to the average tank water temperature for moving said contact brush relatively to the leading edge of said contact plate to cause engagement between said contact plate and said brush earlier when the average temperature of the water in the tank is low than when it is high and electric connections between said movable contact brush, said contact plate and said electromagnetic switch to cause energization of said electromagnetic switch and of the electric heater upon engagement of said brush with said contact plate in case substantially less than all of the water in the tank is hot and a thermally-actuable heater control switch for causing deenergization of the heater when substantially all of the water in the tank is hot.

2. In an off-peak water heating system for a tank having an electric heater, an electromagnetic and a thermally-actuable switch connected in series electric circuit with each other and with the electric heater for-controlling the energization of the heater, a continuously operative timer. an electric conducting plate having a maximum width equal to the length in time of an oil-peak .period, an angularly extending leading edge and brush when the average temperature of the water in the tank is low than when it is high and electric connections between said heater, said two switches and said movable contact brush to cause energization of said electromagnetic switch and of the electric heater upon engagement of said contact brush with said contact plate in case substantially less than all of the water in the tank is hot, to cause deenergization of said heater as soon as substantially all oi. the water in the tank is hot, to cause reenergization of said heater in case theheater was deenergized before the end of an oil-peak period and withdrawal of a substantial quantity of hot water from the tank occurred before the end of an off-peak period.

3. A system as set forth in claim 2 and including a normally open switch operable into momen- 

